Has anyone successfully changed their career after 40 and is now working in a trade for example and is doing well? Or knows about services, resources, support in the UK?

No, still in a low paid, unskilled job, but the hours work well for me. I am doing my own Etsy shop though, which makes me feel better given that I haven’t got a well paying job or a trade. Maybe start a side hustle and see where it goes? 

but with the HMRC crackdown one is limited to less than 1k a year, though? Or how does it work? I mean I don't have the time or space to craft things myself, it would be more like a reseller thing, right?

Yes, you can earn 1k or under tax free, but once you pass that you have to start paying tax, so you need to register as a sole trader with HMRC and fill out your tax return once a year, it’s pretty straightforward, and unless you’re earning a lot of money, a lot of the questions don’t apply. Being a reseller business you’d still have to register with HMRC once you’re earning past the 1k threshold. 

Yes, you can earn 1k or under tax free, but once you pass that you have to start paying tax, so you need to register as a sole trader with HMRC and fill out your tax return once a year, it’s pretty straightforward, and unless you’re earning a lot of money, a lot of the questions don’t apply. Being a reseller business you’d still have to register with HMRC once you’re earning past the 1k threshold.